Means and method for centrifugal casting



Mar. 3, 1925.

A. F. ROCKWELL MEANS AND METHOD FOR CENTRIFUGAL CASTING gnal Filed April 8, 1920 2 Sheets-Sheet l Mar. 3, 1925. 1,528,303

A. F. ROCKWELL MEANS AND METHOD Foa CENNRIFUGAL CASTING original Filed April s, 1920 2 sheets-Sheet 2 Patented Mar. 3, 1925.l

UNITED STATES ALBERT ROCKWELL, OF BRISTOL, CONNECTICUT, ASSIGNOR 'T0 STANDARD STEEL AND BEARINGS INCORPORATED, F

OF DELAWARE.

WILMINGTON, DELAWARE, A CORPORATIONv MEANS AND METHOD FOR CENTRIFUGAI. CASTING. g

Application led April 8, 1920, Serial No. 372,200. Renewed July 12, 1924.

To all whom it may concern.'

Be it known that I, ALBERT F. ROCKWELL, l a citizen of the United States, and a resident of Bristol, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Means and Methods for Centrifugal Casting, of which the following is a specification.

This invention relates to the art of metal casting and particularly to means and the method for producing relatively smallcastings of steel or other refractory metal by a centrifugal process.

Comparatively large castings have heretofore been successfully made by the use of a centrifugal process, but because of a premature chllling and solidifying of smaller masses of metal when subject to the coolinginiuence exerted by the larger masses comprising the casting apparatus, the successful production by centrlfugal process of small castings of refractory metals such as steel has not, so far as I am aware, been heretofore achieved.

I have discovered that this premature chilling and solidifying of molten-metal in forming.v small castings by a centrifugal process can.be prevented by using a mold su drawn from a considerable mass of molten metal contained preferably in the pot or crucible of a furnace. When this mechanism is lowered into the pot or crucible the molds are at once'flled with molten metal, and asa result of the centrifugal force created by the rapid rotation of the mechanism, the molds are held full after the mech anism is withdrawn and is cooled in the air.

no premature solidifying or freezing of the metal in the molds such as has been unavoidable With an attempted use of former con-v structions.

tating in the pot or furnace, and if the pot is suiiiciently large with relation to the mo'ld fmechanism, the metal in contact with and llin the molds continues liquid since it is in e ect a part of the larger body of molten metal filling the [ot and subject to the heat ofthe furnace. -rgj t, is only after the moldort capable of being rapidly rotated at`- 111016611121' Structure:

30 w1 and also being lowered into and with- I find] that with this arrangement there is o long as the mechanism is rov carrying mechanism is lifted out of the crucibleand when the only molten metalfremalnlng in the moldcarrying mechanism is held in the mold by the centrifugal force lcreated by the rapid rotation of the mechanism, that the metal in the molds 'solidities' -in the shape desired.

I find that castings produced by this rocess are not only cheaply produced but ave qualities which give them great superiority for some important purposes. They are, for example, particularly adapted to be cnverted into members of antifriction bearings which haveI to meet onerous requirements These valuable qualities are the result of the operation of centrifugal/force on the body of molten metal within the mold mechanism, great pressure being exerted by this force upon the molten-metal and the denser particles being thrown outwardly from the axis of rotation. If the pot or crucible contains gas bubbles or inert impurities not chemically combined with the metals, these tend to be supplanted in the molds by denser purer metal through the action of centrifugal force. The pressure ofcentrifugal force tends, moreover, to produce iin the metal as it cools a homogeneous mass of desirable .'In the drawing,

`Figure l is a view, artly in side elevation andpartly in vertica section of a. centrifugal casting device embodying the invention.

Figure 2 is a 'sectional view of a modified form-of mold adapted to be used in the de vice shown in Figure 1.'.

Figure 3 is a plan view of a casting obtained by the use of the mold shown in-` Figure Referring to the drawing, in Figure 1 there is shown a casting apparatus embodying the inventionin which a' base member 1` is) provided with lugs 2, to which corresponding lugs onan annular mold-support'- ing device'S can be attached. The annular or cylindrical member 3 is open at its lower end and provided with an inwardly-extending shoulder or shelf membrfl which is arranged to provide immediate supporting en- 190 gagement with the lowermost of aplurality vof tiers of annular mold members 5 formed l or shaft 9 journaled in the end of an arm of steel or any lother suitable material and in any desired conformation, the mold members being shown as L-shaped in section in Figure 1 to thereby provide annular recesses for the production of bearing race rings 6.

The casting device thus constituted is so supported that it can, while rotating, be lowered in a -mass of molten metal 7 contained in the crucible 8 of a suitable furnace, and, for this purpose, is shown with the stem .1 supporting member 3, which 'is detached from the conical seat 13 for the purpose, is filled with a supply of the mold rings 5 which are preferably formed of steel with their masses so proportioned to the masses .of metal adapted to be contained inthe mold chambers or cavities that the exchange of heat units between the mold rings and the casting metal is not suliicient to raise the temperature of the mold rings to the point of melting, or to an `otherwise injurious' degree. I hnd that the use of mold members of steel or other vmetal results in the production of castings having very smooth surfaces so as to dispense with a number of subsequent working operations hitherto necessar before the linal grinding and thus add 1n a substantial degree to the eiciency ofthe process as a whole. l

Thecylindrical mold-supporting member 3 is then clamped into position on the seat D 13, the conical formation of which serves to center the member 3 with relation to the shaft 9 to obviate an unbalanced condition in operation. The assembled casting device is then set into rotation-and lowered into the molten steel or other metal 7, the vent passage 14 roviding for the emission of air from the. camber 15 and the rise of a column of molten metal therein.

Meanwhile `at least that part' of the column of liquid metal withinrthe chamber 15 and in contact with the molds of the casting device has been set into rotation with the molds so that the actionof centrifugal'force subjects the hotmetal within the mold chambers to pressure, and underthe continu- -ing action displaces from these chambers gas bubbles and lighter particles of foreign material which ma be present in the metal,

` and at the same time compresses and convstructure in which all the parts subject to wear are formed of the dense, 'wear-resisting castings produced in the manner` described. In order to produce ball members, molds 16, preferablyv of the general formation shown in Figure 2 are made use of, in which the molds cooperate with each vother to form annular channels 17 opening inwardly, the `channels being enlarged at inv tervals to formspherical cavities 18.

It will beseen that a casting 19 of the form shown in Figure 3will be produced in each mold chamber formed bythe mold members 16 of Figure 2. The spherical enlargements 20 in the casting 19, when the surplus connect-ing metal has been trimmed from them in a punching or other suitable process in either a hot or cold condition, form lthe desired ball members, and 'when these members, as well as the race rings produced by the apparatus shown in Figure l, are round to their final precise dimensions, t ey are ready to be assembled to produce a complete bearing structure.

With the construction described, not onl is it possible to produce relatively smal castings without premature solidifying of the casting metal, but also the casting o eration is conducted in a simple and clea y mannerand without wastage of metal.

What I claim is:

1. `A centrifugal casting device comprising. a rotatablemold member constructed and arranged to -be lat will bodily immersed in and withdrawn from a mass of molten metal.

l2. A centrifugal casting device comprising -a rotatable mold member and means for immersing the mold member in a mass of the molten materia-l from which the castings areto be formed, so as to fill the molds, and said means being operable to withdraw the moldA member from the vessel containing the mass of, material in which it is immersed while it is rotating. v

3. A centrifugal casting device comprising a rotatable mold member, means for immersing the mold member in a mass of molten met-al so as tol lill the molds therewith, means for rotatin the m'oldmember .los

from the vessel containing the mass of metal in which the mold member is immersed while continuing its rotation.

4. A centrifugal casting device comprising a rotatable member carrying molds which are arranged around an interior space so as to open directly into thisspaee toward an axis of rotation extending vertically through this open interior space, the whole arranged so that it may be immersed in a mass of molten metal with ythe said interior space open towardthe bottom of said mass of molten metal so as to cause the molten .metal to flow up freely in said interior space and fillsaid molds as such immersion takes place. l

5. Tlat method of, centrifugal casting which consists in immersinga rotatable annular mold member having a mold cavity opening radially inward in a mass of molten metal, and withdrawing it while rotating and continuing a rotatlon yof the member until the metal cools.

6. The methods of centrifugal casting which consists in rotating an annular mol member having a mold cavity opening radially inw-ardl in a mass of molten metal, and separating t e mass of metal from the metal in said mold cavity while rotating themold and continuing the rotation of the mold until the metal cools.

7. Acentrifugal casting device comprising a -rotatable moldlmember constructed and arranged to be immersed in or withdrawn from a mass of molten metal whilev the member is rotating.

ALBERT F. RIOCKWELL.4 

